This invention relates to an improved gage and system for in-process inspection of contoured parts and automated cutting tool condition compensation during the machining operation.
Two very important manufacturing problems are addressed by in-process inspection of machined workpieces and tool condition compensation, i.e. monitoring the cutting tool during the machining process and compensating for tool wear and breakage. First, part inspection on a separate gaging machine followed by rework is both costly and a source of errors during set-up for remachining. These could be eliminated if the part could be inspected on the machine where it is initially turned. Second, there is a need for in-process compensation of tool wear and prompt detection of worn tools and broken tools. Breakage, for example, must be sensed and the tool withdrawn before there is part damage.
Copending allowed application Ser. No. 580,316 filed Feb. 15, 1984, R. A. Thompson and R. E. Breuning, a continuation-in-part of Ser. No. 304,495 filed Sept. 22, 1981 and now abandoned, describes a method for dealing with these problems. A stationary, unidirectional, passive air gage displacement sensor is used, and therefore the method applied only to straight cuts. A similar solution is also needed for contoured cuts, but it cannot be met by such a sensor whose nozzle is mounted on and is stationary relative to the tool holder. FIG. 1 illustrates the primary difficulty which arises when inspecting a contoured surface with a stationary sensing head. If the probe has a spherical head, it is insensitive to the direction to the target. However, like most probes air gages have flat heads. As such a stationary air gage does not have sufficient range to handle the contouring problem.